爲什麼我得到我的$ mysqli連接的布爾值？

Question

echo gettype($mysqli); 
$mysqli=mysqli_connect("localhost", "ivanmatiasjr", "igm384062", "OnlineStore"); 

if(mysqli_connect_error()){printf("Connection failed: %s\n", mysqli_connect_error());exit();} 

$cat_id = mysqli_real_escape_string($mysqli, $_SESSION['cat_id']);      
$cat_title = mysqli_real_escape_string($mysqli, $_SESSION['cat_title']);     
$item_title = mysqli_real_escape_string($mysqli, $_POST['item_title']); 
$item_price = mysqli_real_escape_string($mysqli, $_POST['item_price']); 
$item_desc = mysqli_real_escape_string($mysqli, $_POST['item_desc']); 
$item_image = mysqli_real_escape_string($mysqli, $_POST['item_image']); 

$sql = "INSERT INTO store_items (cat_id, item_title, item_price, item_desc, item_image) VALUES ('".$cat_id."', '".$item_title."', '".$item_price."', '".$item_desc."', '".$item_image."')"; 
$res = mysqli_query($mysqli, $sql) or die(mysqli_error($res)); 
mysqli_free_result($mysqli); 
mysqli_close($mysqli); 

的錯誤信息是：

警告：mysqli_error（）預計參數1是mysqli的，在C定的boolean：\程序文件（x86）\ Apache軟件基金會\ APACHE2.2 \ htdocs中\第59行的addItemToCategory.php

59行是我的mysqli_query()函數。

Answer 1

mysql_error需要mysqli鏈接作爲參數。您將發送$ res作爲參數。